Analytical Parameters Research Articles

Graphene-Modified Electrode for Linear Sweep Voltammetric Sensing of Catechol

A graphene sample (EGr) was obtained in a single-step synthesis by electrochemical exfoliation of graphite rods. A combination of 0.05 M ammonium sulfate and 0.05 M ammonium thiocyanate was employed, leading to a graphene sample composed of few-layer, multi-layer and graphene oxide flakes. Due to the mild exfoliation conditions, large sheets with linear sizes in the range of tens to hundreds of micrometers were produced. The LSV technique gave information about the effect of catechol concentration on the electrochemical signal of bare and graphene-modified electrodes. Based on the resulting calibration plots, the corresponding analytical parameters (linear range, sensitivity, limit of quantification and limit of detection) were calculated for each electrode. In the case of the EGr/GC electrode the linear range was from 6 × 10−7 to 1 × 10−4 M catechol. The detection limit was low (1.82 × 10−7 M) while the quantification limit was 6 × 10−7 M. The sensitivity was five times higher than that corresponding to bare GC, proving the excellent electro-catalytic properties of the graphene-modified electrode. The practical applicability of the graphene-modified electrode was tested in tap water, obtaining an excellent recovery of 102%.

Advancements in Heavy Metal Detection Using Microneedle Array Technology

Heavy metal and metalloid (HM) exposure poses significant health risks, including cardiovascular disease, cancer, and renal damage. This contamination, prevalent in the Western U.S., involves Arsenic (As), Cadmium (Cd), Uranium (U), and Vanadium (V). Interstitial fluid (ISF) is a source of biomarkers, which can be minimally invasively collected using microneedle array (MA) technology. Our study hypothesized that MA-extracted ISF would facilitate non-invasive HM quantification. We established analytical parameters for HM detection in ISF using inductively coupled plasma-mass spectrometry (ICP-MS), defined baseline ISF HM concentrations in unexposed animal populations, and monitored HM levels in ISF under mixed exposure in animal models. Additionally, we assessed HM levels in ISF and biological fluids from three human subjects. Thirty-six Sprague Dawley rats were divided into cohorts: low-level mixed HMs exposure (5X maximum contaminant level (MCL)); high-level single HM with low-level others (50X MCL for one HM with 5X for others); and unexposed controls. ISF and plasma were collected weekly for eight weeks and analyzed via ICP-MS. Our findings reveal a correlation between ISF and plasma HM levels, underscoring ISF’s potential for real-time monitoring of HM exposure. This study also establishes baseline ISF HM levels, illustrating the feasibility of HM quantification using small ISF volumes.

Beyond heart rhythm: 12 months in the echocardiographic evaluation of cardiac resynchronization

Abstract Introduction Cardiac resynchronization therapy (CRT) is recommended in patients with heart failure (HF), but 1/3 of patients are "non-responders". More recent resynchronization algorithms promote electrical optimization by dynamically adjusting atrioventricular intervals, reducing QRS duration. However, their impact on left ventricular function parameters remains unclear. Objectives The following echocardiographic parameters were evaluated and compared pre-CRT and at 12 months follow-up: left ventricular (LV) diastolic and systolic volume; ejection fraction (LVEF), global longitudinal myocardial strain (GLS), left atrial (LA) volume; and analytical parameters: NT-ProBNP. Methods Retrospective, comparative study of patients who underwent CRT. All patients underwent echocardiographic study and clinical analysis before CRT implantation and at 12 months follow-up. The following echocardiographic parameters were assessed post-procedure: LVEF (Simpson biplane method); LV volumes and LA volumes indexed to body surface area and GLS (GE Echopac). NT-ProBNP values were collected. Results 50 patients (74 ± 1.3 years, 66% men) were studied, 50% with ischemic heart disease. In the comparative analysis before CRT and at 12-month follow-up, statistically significant differences were observed in LV diastolic and systolic volumes (96.5 ± 4.3 ml/m2 vs. 78. 2 ± 4 ml/m2, p=0.001; 65 ± 3 ml/m2 vs. 48 ± 3 ml/m2, p=0.001), with a significant improvement in LVEF at follow-up (33% ± 1.1 vs. 40% ± 1.4, p=0.001) as well as GLS (-7.8% ± 0.3 vs. -11.5% ± 1, p=0.003). LA volume also showed a significant decrease at follow-up (87 ± 4 ml vs. 71 ±3.8 ml). Reverse remodeling was more evident in patients without a history of ischemic heart disease, with a decrease in LV volumes, improved LVEF and GLS. NT-ProBNP levels also decreased significantly at follow-up (1945 ± 294 pg/mL vs. 783 ± 134 pg/mL, p=0.001). Conclusions CRT implantation is a therapeutic option for patients with HF refractory to medical treatment. Recent resynchronization algorithms show good results in reducing LV volumes as well as improving left ventricular function, and the prognosis of these patients.

Early Prognostic Markers for Idiopathic Facial Palsy.

To analyze the prognostic value of markers available at the onset of idiopathic facial palsy. To define the evolution of the episode by tracing changes in facial function over time. This is an observational prospective study on patients with facial palsy consulting in the first 24 hs. The evolution was recorded with photographs and monthly visits. Multivariate analysis was conducted between clinical and analytical parameters determined in the first visit and prognostic outcomes: progression, resolution, and "facial palsy evolution index," which integrates severity of the palsy and duration. Sixty-five patients were included. The mean initial HB grade was III, but 31% of the cases progressed in the following days. Complete recovery was observed in 89.5% of the cases (mean duration of the episode of 48 days), and exposure keratitis in 21.5%, with a mean of 42 days after the onset. Multivariate analysis showed that retroauricular pain and white blood cell count were significantly related to progression (odds ratio [OR] 19.08; 1.49, p < 0.05), incomplete resolution (OR 1/0.04; 1/0.59, p < 0.05), and higher evolution index (12.8; 2.9, p < 0.05). Age was also significantly associated with evolution index (0.27, p < 0.05), and platelet-to-lymphocyte ratio with progression (OR 1.02, p < 0.05). The rest of the parameters did not show an association with prognosis. Retroauricular pain and white blood cell count are early indicators of prognosis in idiopathic facial palsy. Initial examinations may not reflect the maximum grade of weakness reached by the patient. Ocular complications can occur several weeks after the onset, even with mild grades of paralysis. 3 Laryngoscope, 2025.

Boar Sperm Motility Assessment Using Computer-Assisted Sperm Analysis: Current Practices, Limitations, and Methodological Challenges

Spermatozoa are highly specialized male cells that are characterized by a unique ability to move, which is a critical factor for successful fertilization. The relative simplicity of motility assessment, especially in livestock, has made it a widely used parameter for evaluating ejaculate quality or cryopreserved semen in the clinical field, and an advanced tool in reproductive physiology and toxicology research. Technological advances in image analysis and computational methods have substantially increased its accuracy through the use of computer-assisted sperm analysis (CASA) to minimize subjective bias in motility assessments. Nevertheless, this more objective method still presents some significant challenges, including variability in the sample preparation, imaging conditions, and analytical parameters. These issues contribute to inconsistency and impair the reproducibility and comparability of data between laboratories. The implementation of standardized protocols, combined with comprehensive training and rigorous evaluation, can serve to mitigate some of the emerging inconsistencies. In addition, the in vitro conditions under which CASA analyses are performed often differ significantly from the natural environment of the female reproductive tract in vivo. This review discusses the methodologies, critical issues, and limitations of sperm motility analyses using CASA, with a particular focus on the boar as an important agricultural and biomedical model species in which this system is widely used.

P0826 Switching to standard-dose subcutaneous vedolizumab increases the percentage of patients in biochemical remission even in those intensified with intravenous vedolizumab: one year results of a Spanish multicentre observational study

Abstract Background Analyse the percentage of subcutaneous drug persistence and pharmacokinetics in patients undergoing intravenous (iv) vedolizumab after switching to Subcutaneous (sc) vedolizumab. In addition, the relationship between treatment with intensified iv vedolizumab versus patients without intensification. Methods A multicentre, descriptive, observational, and retrospective study of a cohort of 54 patients diagnosed with Ulcerative Colitis (UC) and Crohn´s disease (CD) treated with iv vedolizumab, who underwent a switch to sc vedolizumab. Analyse clinical, biochemical, and analytical parameters; vedolizumab levels during follow-up and need for intensified intravenous treatment in patients on iv vedolizumab treatment and subsequent switch to sc vedolizumab with follow-up during weeks 4, 12, 24, and 52. Results 32 patients (59%) had a diagnosis compatible with UC and 22 patients (41%) with CD. Biochemical remission was achieved in 32 patients (86%). All patients achieved clinical remission. In addition, a progressive increase in vedolizumab levels was evident after switching to sc vedolizumab with statistical significance (p&amp;lt;0.05) during follow-up. Up to 14 patients (25.9%) were on an intensified regimen before switching to sc vedolizumab. All patients were maintained on sc vedolizumab at a dose of 108mg/2 weeks without requiring intensification at medical criteria during the one-year follow-up. Conclusion Up to 20% more patients, after switching from iv to sc vedolizumab, achieved biochemical remission, which was higher in the intensified group (34%), after one year of follow-up with a standard dose of sc vedolizumab.

P0388 Can intestinal ultrasound guide us in the treatment of inflammatory bowel disease?

Abstract Background Intestinal Ultrasonography (IUS) is a useful method for monitoring inflammatory bowel disease. The role of Shear Wave Elastography (SWE) and the relationship with other parameters indicating activity are not yet well understood. Methods The aim was to describe the ultrasound characteristics observed in a cohort of patients with Crohn’s disease (CD) and the changes in therapeutic attitude derived from the results of this imaging test. To evaluate the usefulness of SWE in patients with intestinal strictures to detect fibrosis in comparison with analytical and ultrasound parameters of inflammatory activity. We conducted a single-center, retrospective, observational study of a baseline study including IUS examinations performed in CD patients between May 2022 and February 2023. Results We included 63 IUS in CD patients (60.9% male; mean age 43 ± 17 years). The mean HBI-score was 2.77 (± 2.6). A change in therapeutic approach was made in 32.8% of cases following IUS. Stricture was found in 22 IUS (34.9%), with a mean length of 5.6 ± 2.59 cm. Fat wrapping was observed in 40.9% of cases, and loss of wall stratification in 9.1%. Median SWE of the stricture was 9.05. Calprotectin is directly related to the Limberg scale (p&amp;lt;0.001) and indirectly with the SWE value (p&amp;lt;0.05). Inverse correlation between Limberg scale and SWE value (p&amp;lt;0.05) was observed. Conclusion intestinal ultrasonography facilitates a proactive monitoring in CD because immediate changes in therapeutic approach can be made. The combination of the Limberg scale and the SWE value allow the definition of intestinal strictures. Comparative studies are needed to clarify the usefulness in predicting the degree of fibrosis.

Nonreciprocal unconventional magnon blockade induced by Barnett effect and parametric amplification.

We propose a scheme to achieve nonreciprocal unconventional magnon blockade (UMB) via the Barnett effect in a spinning ferrimagnetic yttrium-iron-garnet sphere coupled to a microwave cavity that interacts with a parametric amplifier. We show that, with a strong cavity-magnon coupling regime, giant nonreciprocal UMB can emerge by appropriately choosing two sets of parameters in this system, i.e., strong magnon antibunching occurs only from one direction of the magnetic field but not from the other side. This nonreciprocity originates from the fact that the Barnett shift induced by the Barnett effect can be adjusted from positive to negative values by changing the magnetic field direction, resulting in different frequencies of the magnon mode. Moreover, we demonstrate that parametric amplification is an indispensable factor for constructing the pathways of quantum destructive interference to achieve strong UMB. Furthermore, we give analytical parameter conditions to realize strong UMB, which is proven to be in great agreement with numerical results. Interestingly, the nonreciprocity against magnon thermal occupation is remarkably enhanced by increasing the amplitude of the driving field. Notably, the critical temperature for observing nonreciprocal UMB is as high as 133 mK, and the sphere needs to spin at MHz values to achieve the UMB effect. Our work provides an avenue to realize nonreciprocal single-magnon devices and has potential applications in quantum information processing and quantum communication.

The metric basis for assessing corporate sustainability

Subject. The article addresses corporate sustainability assessment. Objectives. The purpose is to propose a system of indicators of company's activity, enabling to identify the degree of its environmental, social, and economic sustainability. Methods. The study rests on modeling various metric systems in the field of synthesis of financial and non-financial reporting data. Results. The paper offers a list of social, environmental, and economic analytical business parameters sufficient to diagnose the degree of sustainable development of the company, and the format and principles of non-financial reporting presentation, contributing to increasing its applied usefulness, formalizes the method of obtaining this data, defines the role of model proposed by A.D. Sheremet in the metric pool formation of the economic direction, and the logic of connection between the metrics of social, environmental, and economic directions. Conclusions. The proposed principle of relationship between the parameters allows the developed system of indicators to be integrated into the concept of stability based on the application of the Euler–Venn diagram.

Micro-RNA Signature in CSF Before and After Autologous Hematopoietic Stem Cell Transplantation for Multiple Sclerosis.

MicroRNAs (miRNAs) are regulators of gene expression and have been reported to be dysregulated in people with multiple sclerosis (pwMS). Autologous hematopoietic stem cell transplantation (aHSCT) is an immune-ablative treatment intervention for pwMS. Currently, it is unknown if aHSCT affects expression levels of miRNAs in CSF. We explored the ability of circulating miRNA to discriminate between pwMS and healthy controls (HCs) and investigated whether these miRNAs were affected by treatment with aHSCT. Using quantitative reverse transcription PCR, 87 miRNAs were analyzed in CSF samples of a discovery cohort (baseline: 4 & HC: 4). The top 22 miRNAs discriminating between pwMS and HCs were then analyzed in 187 CSF samples of a validation cohort (pwMS: 50, HC: 32). Samples, failing quality control or being follow-ups to baseline samples with quality control issues, were excluded from further analyses. The remaining 133 samples (HC: 29, MS: baseline: 33, 1 year: 30, 2 years: 26, 3-5 years: 15) were analyzed for expression of the top 22 miRNAs. Twelve miRNAs were dysregulated in pwMS compared with HC (q < 0.05). Associations with clinical and analytical parameters were observed in relation to all 12 miRNAs; however, a cluster of 4 miRNAs (miR-16-5p, miR-21-5p, miR-150-5p, and miR-146a-5p) with strong correlations (r > 0.60, p < 0.001) with multiple parameters was identified. Of the 12 miRNAs, 8 were differentially expressed in pwMS with gadolinium-enhancing lesions at baseline and 4 by prior disease-modifying treatment class (p < 0.05). These 4 miRNAs correlated strongly with each other, decreased after aHSCT, and remained low throughout the follow-up period (p < 0.05). Target and pathway analysis of these revealed association with biological processes affecting cytokine production, inflammatory response, and regulation of myelin maintenance. miRNAs are dysregulated in CSF from pwMS and particularly in patients with less effective treatments and/or higher inflammatory disease activity. A 4-miRNA signature with elevated expression of miR-16-5p, miR-21-5p, miR-150-5p, and miR-146a-5p was recurring in multiple analyses. After intervention with aHSCT, the expression levels approached the levels of the HCs, suggesting a potent treatment effect.

Layered triple hydroxide (NiCoFe-LTH) with g-C3N4 hybrid nanocomposite as an adsorbent for Pb(II) extraction.

Hybrid graphitic carbon nitride (g-C3N4) with layer triple hydroxide (LTH) nanocomposite synthesized using the hydrothermal procedure has been investigated as a novel adsorbent g-C3N4@NiCoFe-LTH in the dispersive solid phase microextraction (DSp-ME) for Pb(II) determination in the food and water samples. The nanocomposite was characterized using FTIR, SEM, SEM-EDX, and XRD techniques. Several analytical parameters were adjusted, including pH, adsorbent quantity, adsorption and elution time, sample and eluent volume, and elution solvent concentration, and found as 8.0, 7.5mg, 60, and 30s, 40mL, 2mL, and 0.5mol/L, respectively. The method's accuracy was also evaluated using matrix effects. The results indicated the LOD as 0.163μg/L, LOQ as 0.54μg/L, and PF as 20. The percent relative standard deviation (%RSD)<10%, and the coefficient of determination (R2) was 0.999, demonstrating excellent precision and linearity. The method's effectiveness was also validated by analyzing certified reference materials (CRMs).

Polycatechol coated cigarette filter as a sorbent for microextraction by packed sorbent of acidic non-steroidal anti-inflammatory drugs (NSAIDs) from wastewater samples

In this study, we employed microextraction by packed sorbent (MEPS) using polycatechol-coated cigarette filters (PCCFs) as a sorbent to extract acidic non-steroidal anti-inflammatory drugs (NSAIDs) from water samples, followed by high-performance liquid chromatographic analysis. The formation of coating on cigarette filter was confirmed by Fourier transform infrared (FT-IR) spectroscopy, UV–vis diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM). The effect of coating parameters on extraction efficiency of acidic NASIDs were investigated and 106.0 mg of Na2CO3, 30.0 mg of catechol and 3 h coating time were selected as optimum conditions. Additionally, other factors affecting the analyte extraction efficiency were optimized including a sample solution pH of 2.0, 700.0 µL of methanol as the elution solvent, 3 sorption cycles, 2 desorption cycles, and a 1.5 ml sample volume. Under the optimum conditions the calibration curves for all three analytes were draw and the analytical performance parameters including linear dynamic range (50.0–1000.0 µg.L−1 for naproxen and diclofenac and 100.0–500.0 µg.L−1 for ibuprofen) with R2 > 0.9982, limit of detection (LOD < 45.3 µg.L−1), precision (RSD% < 6.5), accuracy (recovery% > 90.1) and enrichment factor (EF > 2.7) were evaluated. Finally, this method was successfully used to extract and determine the amount of selected acidic NSAIDs in wastewater samples. The sorbent was cheap, easily prepared, efficient, and even reusable.

Assessment of raw milk and skimmed milk through analytical parameters

Milk, a cornerstone of global nutrition, plays a vital role in human diets due to its rich nutritional profile. Quality assurance of milk, whether raw or skimmed, is critical for ensuring public health and meeting regulatory standards. This review provides a detailed examination of the key parameters for assessing milk quality, focusing on physical, chemical, microbiological, and nutritional aspects. Advanced analytical techniques and their relevance in modern dairy science are discussed, emphasizing their application in detecting adulteration, ensuring safety, and meeting consumer demands. Through an in-depth exploration of each parameter, this article underscores the importance of milk quality assessment in the dairy industry.

Spectrophotometric determination of quercetin using micelles of cetyltrimethylammonium bromide in a low ratio methanol–water mixture

A simple and achievable UV-Vis spectrophotometric method for the micro-quantitative determination of quercetin has been developed and validated. This method relies on the formation of supramolecular assemblies of quercetin (QR) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in a 5 % methanolic aqueous solution. In this solvent medium, CTAB in the presence of QR has a critical micelle concentration of 1.2·10-3 mol l-1 at 24 °C, determined through conductometry. Important analytical parameters such as wavelength, composition of methanol-water mixture, CTAB concentration (cCTAB), and pH were optimized. Under the optimum experimental conditions (l = 397 nm, 5 % methanol as solvent, cCTAB = 2.0·10-3 mol l-1, and pH = 6.0), Beer's law was valid for QR concentrations up to 16.9 mg ml-1. The Ringbom optimum QR concentration range was 1.0 - 16.9 mg ml-1. The method sensitivity was 2.03·104 l mol-1 cm-1 (the molar absorptivity) and 0.13 mg ml-1 (limit of detection). The applicability of the proposed method for quantifying QR in pharmaceutical formulations was demonstrated. Furthermore, the proposed UV-Vis spectrophotometric method was successfully applied to the reliably assay of QR, even in the presence of vitamin C.

A Novel Stability Indicating Analytical Development and Validation of an RP-HPLC Assay Method for the Quantification of Voglibose in Bulk and its Formulation

The investigation developed a new stability-indicating Reverse phase high-pressure liquid chromatographic (RP-HPLC) assay method to quantify Voglibose in bulk and pharmaceutical dosage form. The technique used isocratic elution on an Amino (NH2) column (250x4.6mm, 5µ particle size) with a mobile phase of Phosphate Buffer (pH 6.7) and Acetonitrile (27:73 v/v). The separation was monitored using UV detection at 210 nm. The method was validated, meeting ICH guidelines. The retention time of Voglibose was 6.38 minutes, and the linearity was between 24-56 µg/ml. The limit of detection and quantitation were 0.70 and 2.11 µg/ml, respectively. Analytical performance parameters were determined according to ICH guidelines. The method was simple, precise, accurate, robust, and rapid, making it suitable for quantifying Voglibose in bulk and tablet formulation.

ACECLOFENAC AND DICLOFENAC: A REVIEW ON LIQUID CHROMATOGRAPHY TECHNIQUES

The literature entitles the various analytical techniques like, High Performance Liquid Chromatography, Liquid Chromatography-Mass spectrometry. In this literature we reviewed the various analytical, stability studies, impurity profiling and bio-analytical methods used for the estimation of selected drugs. This review gives the concise and collective information about the analytical validative parameters like Limit of detection (LOD), Limit of Quantification (LOQ), Standard Curve, Accuracy &amp; Precision for the analysis of Aceclofenac and diclofenac alone or combination with other drugs. This review helps to carry out further analytical and Bioanalytical studies on the mentioned drugs.

ORACLE: An analytical approach for T1, T2, proton density, and off-resonance mapping with phase-cycled balanced steady-state free precession.

To develop and validate a novel analytical approach simplifying , , proton density (PD), and off-resonance quantifications from phase-cycled balanced steady-state free precession (bSSFP) data. Additionally, to introduce a method to correct aliasing effects in undersampled bSSFP profiles. Off-resonant-encoded analytical parameter quantification using complex linearized equations (ORACLE) provides analytical solutions for bSSFP profiles. which instantaneously quantify , , proton density (PD), and . An aliasing correction formalism was derived to allow undersampling of bSSFP profiles. ORACLE was used to quantify , , PD, / , and based on fully sampled ( ) bSSFP profiles from numerical simulations and 3T MRI experiments in phantom and 10 healthy subjects' brains. Obtained values were compared with reference scans in the same scan session. Aliasing correction was validated in subsampled ( ) bSSFP profiles in numerical simulations and human brains. ORACLE quantifications agreed well with input values from simulations and phantom reference values (R2 = 0.99). In human brains, and quantifications when compared with reference methods showed coefficients of variation below 2.9% and 3.9%, biases of 182 and 16.6 ms, and mean white-matter values of 642 and 51 ms using ORACLE. The quantification differed less than 3 Hz between both methods. PD and maps had comparable histograms. The maps effectively identified cerebrospinal fluid. Aliasing correction removed aliasing-related quantification errors in undersampled bSSFP profiles, significantly reducing scan time. ORACLE enables simplified and rapid quantification of , , PD, and from phase-cycled bSSFP profiles, reducing acquisition time and eliminating biomarker maps' coregistration issues.

Capillary electrophoresis in parenteral nutrition control – validation of two analytical methods: Amino acids/glucose/glucose-1-phosphate and K/Na/Ca/Mg

ObjectivesProduction of parenteral nutrition bags (PNBs) involves many nutrients: complete control of the production process decreases the risk of error. This study aimed to develop and validate two analytical methods...

Analytical and clinical performance of eight Simoa® and Lumipulse® assays for automated measurement of plasma p-tau181 and p-tau217

BackgroundAmong the Alzheimer’s disease (AD) biomarkers measured in blood, phosphorylated forms of tau (p-tau) have been shown to exhibit a particularly high diagnostic potential. Here, we performed a comprehensive method comparison study, followed by evaluation of the diagnostic performance of eight recent plasma p-tau immunoassays targeting different tau phosphorylation sites, different tau fragments, and that are measured by two distinct platforms.MethodsWe enrolled a cohort of 40 patients with AD at the stage of dementia (AD-dem) characterized by positive CSF A + T + profile, and a control group of 40 cognitively healthy participants (Control), to conduct a comprehensive method comparison for three plasma p-tau181 and five plasma p-tau217 assays run on the Simoa® HD-X™ or Lumipulse® G600II/G1200 platforms. Design of the compared assays differed in regard to: (1) tau phosphorylation site targeted by the capture antibody (T181 or T217), and (2) epitope of the pan-tau detector antibody (N-terminal or mid-region). For each of the assays we determined precision and analytical sensitivity parameters and used Passing-Bablok regression and Bland-Altman plots for pairwise comparison of p-tau181 or p-tau217 assays. Subsequently, we evaluated the diagnostic accuracy of all the assays for discrimination between AD-dem and Control groups.ResultsWe found a strong, positive correlation between all the measurements. Fixed and/or proportional bias was observed for each of compared p-tau181 assay pairs or p-tau217 assay pairs. While both plasma p-tau181 and p-tau217 levels were significantly increased in AD-dem vs. Control groups as measured by all assays, higher median concentration AD-dem/Control fold change and AUC values were observed for p-tau217 (assays range: fold change 3.72–6.74, AUC 0.916–0.956) compared with p-tau181 (assays range 1.81–2.94, AUC 0.829–0.909), independently of the platform used. No significant differences were observed between diagnostic performance of p-tau181 assays or p-tau217 assays targeting tau N-terminus or mid-region.ConclusionsAlthough all plasma p-tau measurements enabled discrimination between clinical groups, p-tau217 assays showed the highest robustness, independently of the pan-tau detector antibody targeting N-terminal or mid-region, and independently of the platform used. Considering the observed method disagreement in measured absolute concentrations, we stress the need for development of certified reference material, harmonizing measurements across different platforms.

A Novel Platform Featuring Nanomagnetic Ligand Fishing Based on Fixed-Orientation Immobilized Magnetic Beads for Screening Potential Cyclooxygenase-2 Inhibitors from Panax notoginseng Leaves.

A novel screening platform based on an Fe3O4@C@PDA-Ni2+@COX-2 ligand fishing combination with high-performance liquid chromatography-mass spectrometry was first designed, synthesized, and employed to screen and identify COX-2 inhibitors from Panax notoginseng leaves. The obtained magnetic nanoparticles exhibit outstanding preconcentration ability that allows for controlling the enzyme orientation to avoid enzyme active site blocking, conformational changes, or denaturing during immobilization. The as-prepared Fe3O4@C@PDA-Ni2+@COX-2 composite was carefully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectrometry (FT-IR), Xray powder diffraction (XRD), thermal gravimetric analyzer (TGA), vibrating sample magnetometer (VSM), and Zeta potential analysis. The analytical parameters influencing the magnetic solid-phase fishing efficiency were optimized by univariate and multivariate methods (Box-Behnken design) by testing a positive control and celecoxib with active and inactive COX-2. Under the optimized ligand fishing conditions, twelve potential COX-2 inhibitors were screened and characterized in Panax notoginseng leaves. The results indicate that the proposed method provides a simple, feasible, selective, and effective platform for the efficient screening and identification of active compounds from Chinese herbal medicine. It has guiding significance for the synthesis and development of novel anti-inflammatory drugs, and provides a reference for the efficient discovery of anti-inflammatory drugs or lead compounds from the complex system of Chinese herbal medicine.